Plateout-resistant thermoplastic resin composition

ABSTRACT

A thermoplastic resin composition, comprises a thermoplastic resin (A) and thermoplastic resin fine particles (C) carrying a colloidal inorganic substance (B), and contains the colloidal inorganic substance (B) in a proportion of 0.01–0.8 wt. % of the total of the thermoplastic resin (A), the colloidal inorganic substance (B) and the thermoplastic resin fine particles (C). The thermoplastic resin composition effectively prevents the plateout without impairing inherent properties of the base thermoplastic resin, by containing the colloidal inorganic substance (B) showing a plateout-prevention effect in a small amount and in a good dispersion state.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

This non-provisional application is a national stage of InternationalPatent Application No. PCT/JP02/007659, filed Jul. 29, 2002, benefit ofwhich is claimed under 35 U.S.C. § 365(c) and which in turn claimsbenefit under 35 U.S.C. § 120 Japanese Laid-Open No. 2001-244452, filedAug. 10, 2001, priority benefit of which is also claimed for the presentnational stage application.

TECHNICAL FILED

The present invention relates to a thermoplastic resin composition whichis plateout-resistant, i.e., less liable to cause plateout duringprocessing or molding thereof.

BACKGROUND ART

Thermoplastic resins are used for various processing or molding methods,such as calendering, injection molding and extrusion, for producingextensive and wide variety of shaped products because of their excellentmoldability and colorability. Ordinarily, depending on a species and ausage, a thermoplastic resin may be blended with various additives, suchas thermal stabilizer, antioxidant, flame-retardant, ultravioletabsorber, lubricant, plasticizer, filler, pigment, antistatic agent,impact modifier, processability modifier, and foaming agent, to form athermoplastic resin composition, which is used for processing ormolding. During the processing or molding, the thus-blended additive canbe separated and precipitated to be deposited on surfaces of metallicparts of processing or molding machines, such as a calender roller, anembossing roller, a mold and an extrusion die. This phenomenon is called“plateout”, and the deposited material is also called “plateout”. Inaddition to the precipitation of such an additive, an impurity or alow-molecular weight component in the thermoplastic resin can also beprecipitated and deposited to result in “plateout” in some cases.Further, “plateout” can be caused by a combination of both of these, ora combination with another factor, in some cases. Thus, in thisdescription, a “phenomenon” of deposition of a component of athermoplastic resin composition on a metallic part surface of aprocessing or molding machine, and also a “deposited material”, areinclusively called “plateout”.

Plateout, when caused, results in inferior products, such as asurface-roughened molded product or a molded product with inferior sizeaccuracy. Further, it becomes necessary to terminate the operation andeffect cleaning for removal of the plateout, which results in a loweringof productivity and requires a troublesome work. In many cases, plateoutis obviated by selecting species and adjusting amounts of components, oradjusting the processing conditions, such as a processing temperature,etc., but the countermeasure has to be selected by trial and errorbecause the measure can be different depending on a cause of theplateout.

In the field of processing of vinyl chloride resin, powdery silicondioxide is known to function as an anti-plateout agent because of itslarge surface area effective for scraping out and absorbing a potentialplateout substance, as described in “Handbook of Polyvinyl ChlorideFormulating”, Edited by Edward J. Wickson, John Wiley & Sons (1993), and“Plastics Additives and Modifiers Handbook”, Edited by Jesse Edenbaum,Van Nostrand Reinhold (1993). While depending on the grade of silicondioxide powder, an amount of 0.3–2% with respect to polyvinyl chloridecompound is described to be effective for preventing plateout.

However, the addition in an amount as large as about 1 wt. % of silicondioxide powder to a polyvinyl chloride compound adversely affects theimpact resistance of the compound and results in a lowering intransmittance undesirably for use as a transparent product.

Further, commercially available silicon dioxide powder has a very lowbulk density and is inferior in powder handling characteristic. Morespecifically, in the case of pneumatically transporting a resincomposition containing silicon dioxide powder added to a thermoplasticresin, the fine powdery silicon dioxide is liable to go out of thesystem because of difficulty in capture thereof by a fine powderrecovery apparatus, such as a cyclone or a bag filter. This is not onlyuneconomical but also undesirable as a possible source of environmentalpollution.

Japanese Patent Publication (JP-B) 5-61302 has disclosed a method ofproviding a synthetic resin powder having improved flowability andanti-blocking property by adding fine powder of oxide of a metal, suchas Si, to synthetic resin powder obtained by coagulation of a graftcopolymer latex. However, the publication lacks any reference toplateout, and according to our review, such a fine powder of oxide ofSi, etc., added by powder blending can only show a very low effect ofplateout prevention.

Japanese Laid-Open Patent Application (JP-A) 8-81605 has disclosed toprevent plateout by adding 0.1–1 wt. part of calcium carbonate finepowder of 0.1–0.5 μm to 100 wt. parts of vinyl chloride resin. Thepublication describes that calcium carbonate fine powder of below 0.1 μmresults in an inferior anti-plateout effect. The publication containsExamples 1 and 2 directed to compositions containing 0.1 wt. part and 1wt. part, respectively, of calcium carbonate fine powder, and Example 2exhibited a sufficient anti-plateout effect, whereas Example 1 exhibiteda lower anti-plateout effect which is considered to be insufficient.This may be construed to be attributable to the lower addition amount ofcalcium carbonate fine powder. According to out knowledge, such calciumcarbonate fine powder as used in the publication suffers fromconspicuous dusting and is not desirable from the viewpoint of operationenvironment, while the publication does not refer to it. Further, inview of its Examples, the publication appears to envisage an opaqueproduct, and a lowering in transparency appears to be inevitable whenapplied to a transparent product.

WO 96/34036 has disclosed an agglomerate of polymer fine particlesobtained by adding a colloidal silica aqueous dispersion to an aqueouspolymer latex and agglomerating the latex to provide such an agglomerateof polymer fine particles having captured therein primary particles ofcolloidal silica, and also a molded product having improved rigidity,toughness and thermal resistance due to the colloidal silica dispersedat a high concentration formed by molding the agglomerate. Thepublication describes that the colloidal silica is preferably added inan amount of 1–500 wt. parts per 100 wt. parts of the polymer and isadded in a range of 25 to 150 wt. parts per 100 wt. parts of thepolymer. Thus, the publication does not refer to any about aprocessability, particularly an anti-plateout effect, of a thermoplasticresin composition containing a lower concentration of colloidal silicaas may be obtained by further blending the above-obtained agglomerate ofpolymer fine particles having captured colloidal silica particles withanother thermoplastic resin.

DISCLOSURE OF INVENTION

A principal object of the present invention is to provide athermoplastic resin composition having effectively suppressed plateoutby containing inorganic fine particles functioning as an anti-plateoutagent in an amount less than before and in a state less adverselyaffecting other properties, inclusive of powder handling characteristic.

As a result of our extensive study for achieving the above-mentionedobject, it has been found possible to provide a thermoplastic resincomposition with effective plateout-resistance without adverselyaffecting various properties inclusive of not only powder characteristicbut also other properties, such as transparency and impact resistance,by blending inorganic fine particles functioning as an anti-plateoutagent with a principal thermoplastic resin (a thermoplastic resin (A)described hereinafter) constituting the thermoplastic resin compositionnot directly but after causing the inorganic fine particles to becarried by separately prepared thermoplastic resin fine particles (oragglomerate thereof) having a good powder characteristic.

Thus, according to the present invention, there is provided athermoplastic resin composition, comprising a thermoplastic resin (A)and thermoplastic resin fine particles (C) carrying a colloidalinorganic substance (B), and containing the colloidal inorganicsubstance (B) in a proportion of 0.01–0.8 wt. % of the total of thethermoplastic resin (A), the colloidal inorganic substance (B) and thethermoplastic resin fine particles (C).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The thermoplastic resin (A) as a principal thermoplastic resin componentof the thermoplastic resin composition of the present invention maycomprise any resin species not particularly restricted, but examplesthereof may include: vinyl chloride resin, chlorinated vinyl chlorideresin, vinylidene chloride resin, styrene resin, acrylic resin,polyester resin, polycarbonate resin, and polyamide resin. Among these,it is particularly preferred to use a vinyl chloride resin to which astabilizer containing at least one metal element selected from the groupconsisting of Pb, Cd, Ca, Zn, Sn, Ba, Mg and Al has been added, since aparticularly remarkable effect of plateout prevention is attainedaccording to the present invention.

The colloidal inorganic substance (inorganic fine particles) (B) used asan anti-plateout agent in the present invention may preferably compriseat least one species of oxides or carbonates of at least one metalselected from the group consisting of Ca, Mg, Ba, Zn, Al, Si and Tihaving a dispersed average particle size (primary particle size) of2–100 nm. Among these, it is particularly preferred to use at least onespecies selected from oxides of Si and Ti, and carbonate of Ca. It ispossible that the inorganic fine particles have been subjected to somechemical or physical surface modification. Too large a dispersed averageparticle size is not preferred because it provides a reduced totalsurface area of the inorganic particles at an identical addition amountto result in an inferior plateout prevention effect, and the resultantmolded product of the thermoplastic resin composition is liable to havea rough surface state because of dispersion failure of the inorganicparticles. A dispersed average particle size of 5–50 nm is particularlypreferred.

As far as the colloidal inorganic substance (B) is carried by thethermoplastic resin fine particles (or agglomerate) (C) in a gooddispersion of such a colloidal particle size as described above, thecolloidal inorganic substance (B) can be supplied in any form notparticularly restricted. In order to retain a good dispersion state inthe above-mentioned colloidal particle size until the colloidalinorganic substance (B) is carried by the thermoplastic resin fineparticles (or agglomerate) (C), however, it is preferred to supply thecolloidal inorganic substance (B) in the form of a colloidal particledispersion in an aqueous or organic dispersion medium. From aconsideration of safety and environmental aspect, an aqueous dispersionliquid is particularly preferred.

The thermoplastic resin fine particles (or agglomerate) (C) comprise apolymer (C) which may be a polymer of at least one species of monomerselected from diene monomers, aromatic vinyl monomers, (meth)acrylateester monomers and nitrile monomers, optionally together with anothercopolymerizable monomer. Examples of the polymer (C) may include: ABSresin (acrylonitrile-butadiene-styrene resin), MBS resin (methylmethacrylate-butadiene-styrene resin), AAS resin(acrylate-acrylonitrile-styrene resin), acrylic polymer impactmodifiers, and polymeric processability modifiers. The polymer (C) maybe added in an amount which can vary remarkably depending on the purposeof addition thereof but may generally preferably be selected from arange of 0.05–50 wt. parts, particularly 0.1–30 wt. parts, per 100 wt.parts of the thermoplastic resin (A).

The polymer (C) may be produced through a process generally used forproduction of synthetic resins, such as emulsion polymerization,suspension polymerization, or bulk polymerization. Among these, emulsionpolymerization is preferred so as to allow the addition of the colloidalinorganic substance (B) to a latex of the polymer (C). The emulsionpolymerization may be performed in the presence or absence of a knownemulsifying agent.

The thermoplastic resin fine particles (or agglomerate) (C) maypreferably have a particle size showing good powder processability ofe.g., at least 50 μm, particularly 70–300 μm. Accordingly, fineparticles of a sufficiently large size as may be produced in suspensionpolymerization can be used, as they are, to carry the colloidalinorganic substance (B). However, in the case of using a polymer latexcapable of providing a preferable carrying state, it is preferred thatthe polymer latex is converted into a slurry, e.g., by coagulation, sothat the polymer fine particles constituting the latex are caused toform an agglomerate thereof.

The thermoplastic resin fine particles (C) may carry the colloidalinorganic substance (B) in various modes including typically (a) a modewherein the colloidal inorganic substance (B) is carried principally inthe form of being attached onto the surface of the thermoplastic resinfine particles (or agglomerate) (C), and (b) a mode wherein thecolloidal inorganic substance (B) is carried principally in the form ofbeing included within the agglomerate of the thermoplastic resin fineparticles (C). While an intermediate state is of course possible, it ispreferred that the mode (b) of inclusion is predominant for the purposeof the present invention.

The above-mentioned state of carrying the colloidal inorganic substance(B) by the thermoplastic resin fine particles (or agglomerate) aimed atby the present invention may be formed in various manners, but it is atleast possible to say that such a state cannot be achieved by dryblending (powder blending) of the thermoplastic resin fine particles (oragglomerate) (C) and the colloidal inorganic substance (B), and it isalmost essential to adopt a wet blending mode wherein at least one ofthe thermoplastic resin fine particles (or agglomerate) (C) and thecolloidal inorganic substance (B) is supplied in the form of adispersion liquid thereof. If it is assumed that only one being suppliedin a dispersion liquid form, it is preferred to supply the colloidalinorganic substance (B) in the form of a dispersion liquid.

More specifically, while there are various methods of forming thethermoplastic resin fine particles (or agglomerate) (C) carrying thecolloidal inorganic substance (B), it is preferred to adopt a method ofadding a dispersion liquid of the colloidal inorganic substance (B) to aonce-dried powder of the polymer (C) and drying the mixture; a method ofadding the dispersion liquid of (B) to a slurry of the polymer (C) andde-watering and drying the mixture; a, method of adding the dispersionliquid of (B) to a wet cake of the polymer (C) obtained by de-watering aslurry of the polymer (C) and then drying the mixture; a method ofadding the dispersion liquid of (B) to a latex of the polymer (C) andseparating and drying the solid matter of the mixture, etc. Among these,it is preferred to adopt the method of separating a solid matter from amixture liquid of the polymer latex (C) and the colloidal inorganicsubstance (B). The separation of a solid matter from a mixture liquid ofthe polymer latex (C) and the colloidal inorganic substance (B) may beperformed by any methods, inclusive of a spray drying method; a methodof spraying the mixture liquid into an acidic medium to effectco-coagulation, followed by de-watering and drying; a method ofco-coagulation with an acid or a salt, followed by de-watering anddrying; a freeze-drying method, etc. In the course of the drying or theco-coagulation, the fine particles of the polymer (C) constituting thelatex are naturally caused to form an agglomerate including thecolloidal inorganic substance (B). Among the above, the method ofco-coagulation followed by dewatering and drying is most preferred inorder to provide a higher degree of inclusion of the colloidal inorganicsubstance (B).

To the polymer (C), an additive, such as a thermal stabilizer, ananti-oxidant, an ultra-violet absorber, or an anti-blocking agent, maybe added as desired. These additives may be added to the latex of thepolymer (C) or after the conversion thereof into a slurry or a powder.

The thermoplastic resin composition of the present invention may beobtained by blending the thermoplastic resin (A) with the thermoplasticresin fine particles (C) carrying the colloidal inorganic substance (B)so as to contain 0.01–0.8 wt. %, preferably 0.05–0.3 wt. %, of (B) withrespect to the total amount of (A), (B) and (C). For the blending, ablender, such as a Henchel mixer or a Bambury mixer, may be used. At thetime of blending, it is possible to add an additive, such as an impactresistance modifier, a processability modifier, the thermal stabilizer,an anti-oxidant, a flame-retardant, an ultraviolet absorber, aplasticizer, a lubricant, an anti-static agent, an anti-fungus agent, afiller, a pigment, or a foaming agent. The resultant thermoplastic resincomposition may be subjected to various processing or molding processes,such as calendering, extrusion molding, blow molding, and injectionmolding. Thus, in the present invention, the term “plateout” not onlymeans a narrower sense of plateout onto a calender roller surface butbroadly refers to attachment of gluey substance at dies, deposition ininjection molds, etc., resulting from plateout.

Hereinbelow, the present invention will be described more specificallybased on Examples, which however should not be construed to restrict thescope of the present invention in any way. In the following Examples,“part(s)” means “part(s) by weight” unless otherwise noted specifically.

<Measurement Methods>

Various physical properties described herein are based on valuesmeasured according to the following methods.

Average Particle Size of Colloidal Particles

Average particle sizes of colloidal particles in aqueous dispersionliquids were measured by using an apparatus (“N4SD”, made by CoulterElectronics Inc.) according to the dynamic light scattering method.Average particle size values for dry colloidal particles have been takenfrom a technical brochure issued by a supplier.

Dry Powder Average Particle Size and Fine Powder Fraction

A powder sample in 50 g blended with 0.5 g of carbon black was subjectedto sieving on a stack of screens having openings of 850, 500, 355, 300,250, 212, 150, 106 and 45 μm, respectively, and the weight percentagesof powder fractions on the respective screens with respect to the totalpowder were plotted on a Rosin-Ramler digram to determine a particlesize giving cumulatively 50 wt. % as an average particle size(50%-average particle size, sometimes denoted by D_(50%)). Further theweight percentage of a powder fraction passing through the 45 μm-screenwith respect to the total powder weight was taken as a fine powderfraction.

Plateout

A sample thermoplastic resin composition was melt-kneaded for 2 min. ontest rollers each having a diameter of 150 mm and a width of 400 mmunder the conditions of a roller gap of 0.25 mm, 198° C. and 13 rpm, andthe gloss on the roller surfaces was evaluated by observation with eyes.The plateout level was evaluated at 5 levels ranging from a level Arepresenting no roller surface fog due to plateout on the rollersurfaces to a level E representing conspicuous fog on the rollersurfaces.

Impact Strength

A resin sheet obtained after the roller kneading in the above plateouttest was hot-pressed at 200° C. into a 3 mm-thick press-molded sheet,which was subjected to measurement of an impact strength at 23° C.according to JIS K7110.

Transparency

A resin sheet obtained after the roller kneading in the above plateouttest was hot-pressed at 200° C. into a 3 mm-thick press-molded sheet,which was subjected to measurement of a haze value by a haze meter.

<Synthesis of Polymers (C)>

SYNTHESIS EXAMPLE A Diene-Type Rubber-Containing Graft Polymer

Into a pressure-resistant vessel equipped with a stirrer,

distilled water 200 part(s) tetra-sodium pyrophosphate 1.5 part(s)ferrous sulfate 0.002 part(s) di-sodium ethylenediaminetetraacetate0.005 part(s) dextrose 1 part(s) potassium oleate 1 part(s)diisopropylbenzene hydroperoxide 0.4 part(s)were charged, and after replacement with nitrogen,

butadiene 75 part(s) styrene 25 part(s) t-dodecylmercaptan 0.3 part(s) were added. The reaction was performed for 8 hours at 60° C. to obtain adiene-type rubber latex having an average particle size of 0.12 μm.

To 210 parts (including 70 parts of solid matter) of the rubber latex,

distilled water  60 part(s) sodium formaldehydesulfoxylate 0.6 part(s)were added, and while the system was held at 70° C., a mixture of

methyl methacrylate  15 part(s) cumene hydroperoxide 0.2 part(s)was added dropwise in 1 hour, followed by holding for 3 hours.Thereafter,

sodium formaldehydesulfoxylate 0.6 part(s)was added, and while the system was held at 70° C., a mixture of

styrene  15 part(s) cumene hydroperoxide 0.2 part(s)was added dropwise in 1 hour, followed by holding for 3 hours, tocomplete the polymerization, whereby Polymer latex (a) having an averageparticle size of 0.13 μm was obtained.

SYNTHESIS EXAMPLE B Acrylic Copolymer

Into a pressure-resistant vessel equipped with a stirrer,

distilled water 200 part(s) sodium dodecylbezenesulfonate  2 part(s)potassium persulfate  0.1 part(s)were charged, and after replacement with nitrogen, the system was heldat 70° C. under stirring. Then, a mixture of

methyl methacrylate 60 part(s) n-butyl methacrylate 40 part(s)was added dropwise in hours, followed by holding for 2 hours to completethe polymerization, whereby Polymer latex (b) was obtained.[Synthesis Example c] Acrylic Rubber-Containing Graft Copolymer

Into a pressure-resistant vessel equipped with a stirrer,

distilled water  200 part(s) boric acid 0.45 part(s) anhydrous sodiumcarbonate 0.045 part(s)  potassium oleate   2 part(s) potassiumpersulfate 0.15 part(s)were charged, and after replacement with nitrogen, the system was heldat 70° C. under stirring. Then, a mixture of

n-butyl acrylate 49.8 part(s) divinylbenzene  0.2 part(s)was added dropwise in 3 hours, and the system was further held for 1hour. Thereafter,

potassium persulfate 0.15 partwas added, and while the system was held at 70° C., a mixture of

n-butyl acrylate 49 part(s) alkyl acrylate  1 part(s)was added dropwise in 3 hours, followed by holding for 1 hour, to obtainan acrylic rubber latex having an average particle size of 0.24 μm.

To 210 parts (including 70 parts of solid matter) of the rubber latex,

distilled water   60 part(s) potassium persulfate 0.15 part(s)were added, and while the system was hold at 70° C., a mixture of

methyl methacrylate 25 part(s) styrene  5 part(s)was added dropwise in 2 hours, followed by holding for 2 hours tocomplete the polymerization, whereby Polymer latex (c) was obtained.

EXAMPLE 1

Polymer latex (a) containing 100 parts of solid matter and 2.5 parts(solid matter=1 part) of a colloidal silica aqueous dispersion liquid(“SNOWTEX ST-XL”, made by Nissan Kagaku Kogyo K.K.) containing colloidalsilica (as colloidal inorganic substance) having an average particlesize of 50 nm were mixed with each other. The mixture exhibited anaverage particle size of 0.13 μm which was not larger than that inPolymer latex (a). To the mixture, 0.5 part of butylated hydroxytoluenewas added, and the resultant mixture was added gradually to 1000 partsof a 0.5 wt. %-aqueous sulfuric acid solution (coagulant) held at 40° C.under stirring. Then, the mixture was neutralized with a 10 wt.%-potassium hydroxide aqueous solution, and after being heat-treated atan increased temperature of 90° C., the mixture was de-watered and driedto obtain an inorganic substance-containing polymer powder (ofD_(50%)=ca. 150 μm). Incidentally, the filtrated liquid during thede-watering was clear. As a result of observation of a cross-section ofthe inorganic substance-carrying polymer powder, the inorganic particleswere taken inside the polymer and in a form of being substantiallyincluded therein. The inorganic substance-carrying polymer powderexhibited a fine powder fraction of 4.5 wt. % and was found to be apowder causing little dusting.

A vinyl chloride resin (“S9008”, made by Kureha Chemical Industry Co.,Ltd.) was blended with 15 parts of the above-prepared inorganicsubstance-carrying polymer powder, 2.5 parts of Ca—Zn-based stabilizer(“Irgastab CZ122”, made by Witco Co.), 0.25 part of stearic acid, 0.3part of aliphatic amide wax (“Henkel Loxiol EBS”, made by Henkel Co.),2.5 parts of epoxidized soybean oil and 2.0 parts of an acrylic polymerprocessability modifier by means of a Henchel mixer, to prepare athermoplastic resin composition.

The thermoplastic resin composition was subjected to evaluation ofPlateout, Impact Strength and Transparency (Haze) according to theabove-described methods. The results of the evaluation are shown inTable 1 appearing hereinafter together with those of thermoplastic resincompositions prepared in the following Examples.

EXAMPLE 2

A thermoplastic resin composition was prepared in the same manner as inExample 1 except for using an inorganic substance-carrying polymerpowder, which was prepared in a similar manner as in Example 1 exceptthat Polymer latex (a) without being mixed with colloidal silica wasconverted into a polymer slurry, and the polymer slurry was blended with1 part (as solid matter) of the colloidal silica aqueous dispersionliquid having an average particle size of 50 nm (“SNOWTEX ST-XL”, madeby Nissan Kagaku Kogyo K.K.), followed by dewatering and drying.

EXAMPLE 3

A thermoplastic resin composition was prepared in the same manner as inExample 1 except for using an inorganic substance-carrying polymerpowder, which was prepared in a similar manner as in Example 1 exceptthat Polymer latex (a) without being mixed with colloidal silica wasdried as it was into a polymer powder, and the polymer powder(D_(50%)=ca. 150 μm) was blended with 1 part (as solid matter) of thecolloidal silica aqueous dispersion liquid having an average particlesize of 50 nm (“SNOWTEX ST-XL”, made by Nissan Kagaku Kogyo K.K.),followed by further drying.

EXAMPLE 4

A thermoplastic resin composition was prepared in the same manner as inExample 1 except for using an inorganic substance-carrying polymerpowder, which was prepared in a similar manner as in Example 1 exceptthat Polymer latex (a) was blended with 0.2 part (0.08 part as solidmatter) of a colloidal silica aqueous dispersion liquid having a solidmatter content of 40 wt. % and an average particle size of 15 nm insteadof 1 part (as solid matter) of the colloidal silica aqueous dispersionliquid having an average particle size of 50 nm (“SNOWTEX ST-XL”, madeby Nissan Kagaku Kogyo K.K.).

COMPARATIVE EXAMPLE 1

A thermoplastic resin composition was prepared in the same manner as inExample 1 except for using instead of the inorganic substance-carryingpolymer powder a dry polymer powder, which was prepared by treatingPolymer latex (a) similarly as in Example 1 except for omitting thecolloidal silica aqueous dispersion liquid.

COMPARATIVE EXAMPLE 2

A thermoplastic resin composition was prepared in the same manner as inExample 1 except for using instead of the inorganic substance-carryingpolymer powder a dry polymer-inorganic substance powder mixture, whichwas prepared in a similar manner as the inorganic substance-caringpolymer powder in Example 1 except that Polymer latex (a) without beingcolloidal silica was dried as it was into a polymer powder, and thepolymer powder was blended with 1 part (solid matter) of fine powderysilica having an average primary particle size of 30 nm (“AEROSIL 50”,made by Nippon Aerosil K.K.).

COMPARATIVE EXAMPLES 3 and 4

A thermoplastic resin composition was prepared in the same manner as inExample 1 except for using instead of the inorganic substance-carryingpolymer powder two types of inorganic substance-carrying polymerpowders, which were prepared in a similar manner as the inorganicsubstance-carrying polymer powder in Example 1 except for changing theamount of the colloidal silica aqueous dispersion liquid (“SNOWTEXST-XL”, made by Nissan Kagaku Kogyo K.K.) to 10 parts and 0.01 part,respectively as solid matter as shown in Table 1, instead of 1 part (inExample 1).

EXAMPLE 5

A thermoplastic resin composition was prepared in a similar manner as inExample 1 except for adding instead of 15 parts of the inorganicsubstance-carrying polymer powder 2 parts of an inorganicsubstance-carrying polymer powder which was prepared in a similar manneras in Example 1 except for using Polymer latex (b) instead of Polymerlatex (a), changing the amount of the colloidal silica aqueousdispersion liquid to 5 parts (as solid matter), and changing thecoagulant to a 1 wt. % aluminum sulfate aqueous solution withoutneutralization, and adding 20 parts of an impact strength modifier forvinyl chloride resin (“BTA 712”, made by Kureha Chemical Co., Ltd.)instead of the 2 parts of an acrylic polymer processability modifier,respectively, per 100 parts of the vinyl chloride resin, as shown inTable 1.

EXAMPLE 6

A thermoplastic resin composition was prepared in the same manner as inExample 1 except for using an inorganic substance-carrying polymerpowder, which was prepared in a similar manner as in Example 1 exceptfor using Polymer latex (c) instead of Polymer latex (a).

The thermoplastic resin composition was evaluated in the same manner asin Example 1, but the measurement of a haze values was not measuredsince the molded product was apparently opaque.

As shown in Table 1, Examples 1–4 are directed to examples of thethermoplastic resin composition according to the present inventioncontaining inorganic substance-carrying polymers formed by addingcolloidal inorganic substance and exhibited clearly less plateoutcompared with the thermoplastic resin composition of Comparative Example1 obtained without adding an inorganic substance. The thermoplasticresin compositions of Examples 1–4 caused little dusting and were freefrom lowering in other physical properties.

The thermoplastic resin composition of Comparative Example 2 obtained bypowder blending of fine powdery silica with a polymer (C) after drying,was not only inferior in plateout resistance but also somewhat inferiorin dusting resistance, transparency and impact strength.

The thermoplastic resin composition of Comparative Example 3 obtained byadding an excessively large amount of colloidal silica aqueousdispersion liquid, was poor in handling characteristic because of theoccurrence of much dust in addition to a difficulty that a substantialproportion of colloidal inorganic substance was not sufficientlycoagulated but discharged out of the system.

The thermoplastic resin composition of Comparative Example 4 exhibitedlittle improvement in plateout resistance because of a small amount ofaddition of the colloidal silica aqueous dispersion liquid.

The thermoplastic resin composition of Example 5 obtained by adding apolymer processability modifier as a polymer (C), exhibited an excellentplateout resistance, maintained a transparency and did not obstruct thestrength-improving effect owing to the addition of an impact strengthmodifier (“BTA 712”).

The thermoplastic resin composition of Example 6 obtained by using anacrylic impact-resistance modifier as a polymer (C), similarly exhibiteda good plateout resistance while not obstructing the improvement inimpact strength.

TABLE 1 Example 1 2 3 4 Comp. 1 Comp. 2 Comp. 3 Comp. 4 5 6 Polymer (C)latex (a) (a) (a) (a) (a) (a) (a) (a) (b) (c) Inorganic substance (B)Type *1 SiO₂(C) SiO₂(C) SiO₂(C) SiO₂(C) — SiO₂(P) SiO₂(C) SiO₂(C)SiO₂(C) SiO₂(C) Average particle size [nm] *2 50 50 50 15 — 30 50 50 5050 Amount (solid) [wt. parts] 1 1 1 0.08 — 1 10 0.01 5 1 State ofpolymer (C) latex slurry powder latex — powder latex latex latex latexat the time of adding (B) State of filtrate liquid clear clear — clearclear — turbid clear clear clear Fine powder fraction [wt. %] 4.5 4.84.9 3.8 3.8 5.3 8.4 4.4 5.1 4.2 Dusting little little little littlelittle noticeable severe little little little Amount of (B) + (C) [wt.parts] 15 15 15 15 15 15 15 15 2 15 Amount of BTA 712 [wt. parts] — — —— — — — — 20 — Amount of K-130P [wt. parts] 2 2 2 2 2 2 2 2 — 2(B)/(A) + (B) + (C) [wt. %] 0.13 0.13 0.13 0.010 0 0.13 1.3 0.0013 0.0780.13 Plateout A A B B E D A E A A Haze [%] 3.6 3.5 3.9 3.2 3.2 6.5 17.83.4 3.2 — Impact strength [kJ/m²] 124 126 122 130 130 109 32 124 132 126*1SiO₂(C) represents colloidal silica added as an aqueous dispersionliquid, and SiO₂(P) represents colloidal silica added as dry finepowder. *2The average particle size of SiO₂(P) is a primary particlesize value shown in a technical brochure from the supplier.

INDUSTRIAL APPLICABILITY

As described above, according to the present invention, there isprovided a thermoplastic resin composition, which contains a colloidalinorganic substance showing a plateout-prevention effect in a smallamount and in a good dispersion state, and as a result thereof,effectively prevents the plateout without impairing inherent propertiesof the base thermoplastic resin.

1. A thermoplastic resin composition, comprising a thermoplastic resin(A) and thermoplastic resin fine particles (C) carrying a colloidalinorgarnic substance (B), and containing the colloidal inorganicsubstance (B) in a proportion of 0.01 –0.8 wt. % of the total of thethermoplastic resin (A), the colloidal inorganic substance (B) and thethermoplastic resin fine particles (C).
 2. A thermoplastic resincomposition according to claim 1, wherein the thermoplastic resin fineparticles (C) assumes an agglomerate structure.
 3. A thermoplastic resincomposition according to claim 2, wherein the colloidal inorganicsubstance (B) is carried principally in the form of being attached ontoa surface of the thermoplastic resin fine particle agglomerate (C).
 4. Athermoplastic resin compostion according to claim 3, wherein thethermoplastic resin fine particle agglomerate (C) carrying the colloidalinorganic substance (B) has been obtained by mixing a slurry comprisinga coagulated latex of polymer forming the thermoplastic resin fineparticle agglomerated (C) with the colloidal inorganic substance (B),and then drying the mixture.
 5. A thermoplastic resin compositionaccording to claim 2, wherein the colloidal inorganic substance (B) iscarried principally in the form of being included within thethermoplastic resin fine particle agglomerate (C).
 6. A thermoplasticresin composition according to claim 5, wherein the thermoplastic resinfine particle agglomerate (C) carrying the colloidal inorganic substance(B) has been obtained by mixing a latex of polymer forming thethermoplastic resin fine particle agglomerate (C) with the colloidalinorganic substance (B), and then subjecting the mixture to coagulationof the polymer latex and drying.
 7. A thermoplastic resin compositionaccording to claim 6, wherein the colloidal inorganic substance (B)mixed with the polymer latex is in the form of a colloidal dispersionliquid.
 8. A thermoplastic resin composition according to claim 1,wherein (a) the colloidal inorganic substance (B) comprises at least oneof oxides and carbonates of at least one metal selected from the groupconsisting of Ca, Mg, Ba, Zn, Al, Si and Ti in the form of fineparticles having an average particle size of 2–100 nm, and (b) thethermoplastic resin fine particles (C) comprise fine particles ofpolymer of at least one species of monomer selected from the groupconsisting of diene monomers, aromatic vinyl monomers, (meth)acrylatemonomers and nitrile monomers, and are contained in a proportion of0.05–50 wt. parts per 100 wt. parts of the thermoplastic resin (A).
 9. Athermoplastic resin composition according to claim 1, wherein thethermoplastic resin (A) is a vinyl chloride resin, and the thermoplasticresin composition further contains a stabilizer comprising at least onemetal selected from the group consisting of Pb, Cd, Ca, Zn, Sn, Ba, Mg,and Al.